The goal of this prospective study is to define and determine predictors of the natural course of physical health status, health services utilization, and self-reported compliance with prescribed treatment among a community cohort of homeless adults. Particular attention will be given to documenting the effects of mental illness, substance abuse, and changes in housing (i.e., an exit from or reentry into homelessness). The results will yield a better understanding of factors that facilitate or hinder medical treatment among homeless persons and how to develop effective interventions to address their medical treatment needs. A stratified representative sample of 480 homeless adults in two Los Angeles sites, drawn as part of an NIMH study of course of homelessness, will be interviewed and undergo limited screening physical examinations every 6 months for 18 months. Respondents will rate their perceived general and current health status, and will report physical functional status, restricted activity days, and five serious physical symptoms. They will also be evaluated for the presence of four specific monitored health conditions that are highly prevalent within this population, cause pain or worry to the respondent, are potentially disabling, or if untreated, could have serious health consequences: high blood pressure, vision impairment, and skin/foot disorders will be examined at 6-month intervals, and tuberculosis at the first and last data collection periods. Respondents who screen positive for a condition will be advised to seek medical care for it, and will be given a list of health facilities that provide free or affordable medical care. At each data collection period, respondents will be surveyed for the status of the four monitored conditions, and related health services utilization, prescribed therapy, and perceived barriers to obtaining care and to complying with prescribed care. This study will take advantage of an existing NIMH study of the RAND Corporation, that begins data collection in October 1, 1990. The NIMH study will determine psychosocial predictors of course of homelessness (probability of exits and reentries over two years). By utilizing the sampling and data collection efforts of this larger, already funded, project the budget for this study can be kept to a minimum: the NIMH study will bimonthly assess mental health, substance abuse, and housing status.